Prioritization of Abandoned Mine Sites in California

The state of California has 47,000 abandoned mine sites from two hundred years of extensive mining activities. Approximately 5000 of these sites in California pose massive environmental contamination problems, including toxic tailings piles, waste pits, abandoned processing areas, inhalation hazards, and continuous contaminant releases to surface water and groundwater resources. Antiquated mining laws in place today in the United States still do not account for the true environmental cost of mining.
The massive scope of abandoned mines in California combined with the scientific and financial limitations to address them necessitates a sound ranking process. Abandoned mine sites threaten human and ecological communities with contamination impacts to groundwater, surface water, and soils. A prioritization system is needed in California to better account for the most environmentally hazardous abandoned mines based on human health risks, ecological toxicity, relative size and severity, persistence of contaminants, and cost of remediation.
By examining literature studies and existing prioritization efforts, this project seeks to condense and illustrate consideration factors that may assist California regulators in strategic decision-making. Lines of evidence identify acid mine drainage, mercury, and arsenic contamination as the highest priority types of contamination issues posed by orphaned mine sites. This study is intended to provide insight to decision makers as they determine how to best solve a seemingly insurmountable environmental problem.